In the field of printing production, the application of digital information processing and computer control technologies has become increasingly widespread and in-depth. For some time, people have come into contact with concepts such as "Digital workflow" and "Integration of production processes" and have already made some preliminary attempts.
As a whole concept of contact pre-press processing, printing and post-press processing, “digital workflow” integrates the above three sub-processes into an inseparable system based on digital production control information, making digitalized graphic information complete and accurate. Transfer, and finally processed into a printed product.
The formation and progress of digital workflow in the field of printing industry will inevitably promote the further development of the printing industry in the digital environment, increase its competitive strength, and play an important role in the exchange of information with other areas.
First, the printing process and its accompanying information flow
As we are familiar with, the tasks undertaken by printing technology are mainly twofold:
1. Information dissemination: information is transmitted to the public through books, publications, newspapers and other information carriers;
2. Auxiliary processing of consumer products: Printing-related auxiliary processing is provided in the packaging and decorating industry, etc. to provide consumers with beautiful and practical consumer products to achieve the purpose of beautifying and improving the quality of life.
In general, the printed product needs to be processed through three steps of prepress processing, printing, and postpress processing. To accomplish these tasks efficiently and with high quality, it is necessary to constantly optimize from the technical and managerial level to reduce the consumption of time, materials, manpower, etc., and also reduce the impact of various factors that adversely affect the quality of printed products. Make the production run smoother and the product quality stable at a higher level.
In the production of printing industry, from a technical point of view, there are indeed two kinds of technical information flow, namely: "text and information flow" and "production control information flow." Of course, each company has "non-technical management information flow." "In order to make reasonable arrangements for all aspects of the company. This article focuses on the discussion of the first two kinds of information flow.
Graphical information flow is the information that needs to be printed and transmitted to the public, such as the text, graphics, and images submitted by the customer.
Control information flow is the necessary control information for the correct production and processing of printed products, such as: printed product specification information (layout, dimensions, processing methods, modeling data), quality control information required for printing processing (printer ink control data, Postpress processing data, etc.), equipment scheduling information for printing jobs, etc.
Print production technology has experienced different stages of development, and the expression and relevance of these two types of information flow are also different.
In these two types of information flow, the digitization and digitization of graphic information has gone through a long process. The development of printing plate and printing technology has experienced many stages of pure handwork, chemical/photochemical/mechanical, electronic and digital. Obviously, in the stages of “carving knife+metal plate”, “lead alloy+powder pot (lead and fire)”, “photo and etching solution”, text, graphics, and image information always appear in some physical form, and Non-digitized representation and transmission.
In the evolution of technology, purely mechanical platemaking and printing equipment first appeared instead of manual production, and electronic control machines and digitally controlled plate making, printing, and postpress processing machinery equipment, that is, control information, gradually emerged. Digitization is achieved with the advent and development of numerical control technology.
When it comes to the development of printing technology, people always give priority to the development of related equipment and materials, from "lead and fire" to "light and electricity", and then to "computer-making, printing" as "Coputer To X" technology. These are the results of people's unremitting efforts.
At the stage of photochemistry/chemistry and mechanics, the graphic and textual information is transmitted in the form of manuscripts, photographs, color separation films, printing plates, etc., and the production control information flow is expressed in the form of dictation, subpena, order, etc. transfer. Both types of information flow have nothing to do with digitalization.
Due to the advancement of electronic technology, the appearance of electronic color separation machines has enabled graphic reproduction to enter the electronic and partial digitization stages. At the same time, the text information also entered the computer processing stage. At this point, the graphic and information flow has reached the goal of digitization and partial digitization. Production control information flow is also managed by a small number of computers. At this stage (computer typesetting/electronic color separation), the degree of correlation between the two types of information flow is still low.
“Desktop Publishing Technology (DTP)” is a period of revolutionary change in the digitization of graphic and text information and the extensive application of computer information processing in prepress processing. After its baptism, the information flow has been fully digitized.
At this stage, people use a keyboard to input text, use a mouse, and use a digital tablet to perform graphic input, apply a scanner to digitize images, perform typesetting, graphic composition, graphic processing, image correction, and editing in a computer. Printing color separation and other processing, eventually forming a computer language description of the printed page, and use "RIP" to form a layout information that can be recorded, output component color film through a laser phototypesetting machine and other equipment, after printing, printing to get printed matter, and then after printing Processing to obtain the final printed product.
Due to the "open architecture" of the DIP system, there is no obvious obstacle to the transmission of graphic and textual information between various prepress systems. Taking the appearance of the "Direct Imaging (DI) Press" in 1991, the flow of graphic and text information broke through the limitations of the prepress area and was passed on to the printing press for plate making and printing, demonstrating the prevalence of all-digital informatization. At this stage, the printer also achieved full computer digital control.
At this point, it should be noted that the digitized process flow for the dissemination of information has been established, but the production and delivery mechanisms for production control information have not been completely established in the entire process, and the production control information flow cannot be smoothly integrated with the graphic and information flow. One.
As the digitization of information continues to deepen, the digitalization of production control information flow is gradually realized. Currently, "integrated integration" of graphic information flow and production control information flow has been realized.
In 1993, initiated by Heidelberg Druckmaschinen AG, dozens of prepress, printing and postpress companies participated in the establishment of the CIP3 organization. At the Drupa Fair in 2000, the organization changed CIP3 to CIP4. Its basic aims were:
In the entire printing process, from the beginning of the printing task and the pre-press processing, various digital production control information is collected and acquired, and is continuously updated along with the graphic reproduction process, and is gradually transmitted to the printing and post-press processing processes. On the equipment involved, the printing and postpress processes are controlled so that the entire production process and the status of the production equipment are under the control of the production control information flow, achieving the goal of reasonable, efficient, and high-quality production.
We can clearly see that in the face of increasingly fierce competition, in order to continuously improve the efficiency and quality of printed products, various control information in the process of prepress, printing, and postpress processing is incorporated into computer management, and digital control information is used. Flow connects the entire printing production process. This is the basic tenet of the “digital workflow”. The establishment of an integrated digital workflow is a more full and effective application of graphic and textual information flow and production control information flow at a higher level than ever to obtain higher benefits. This is also the work of CIP3/CIP4 organizations. The ultimate goal.

Second, the digitization of information
The emergence and development of electronic and computer technologies have established binary digital representations of information. The digitization of information refers to binary 0/1 digital representation information that is easily identified and processed by a computer.
The aforementioned two kinds of information flow contain a variety of information. The information has different characteristics and its digital characteristics are also different.
1. Digitization of text information
Non-digitized textual information exists in the form of "graphical symbols." People observe the appearance (image) of text characters, and make their “original appearance” into photographic paper, film and printing plates through complex processes, and then print them on paper and other materials.
The digitization of textual information consists of two aspects: encoding and font description.
(1) The encoding of text, that is, a multi-bit binary digit for each character. For the Spanish language, the use of 8-bit binary digits (1 byte) to indicate that the word symbol is sufficient (28); but for Chinese characters with a large number of characters, it requires at least 16 bits (2 bytes) to Representation (216).
(2) Digitization of text glyphs, that is, the "pattern" of text is represented by a binary number. The simplest way to achieve this is to use the text strokes and spaces as 1 and 0, respectively, to form a "matrix font." The more commonly used font digitization method is to represent the outline of the text as binary data (contour glyphs), and to restore the outline to dot matrix information when the text “appearance” (display/recording) is required.
2. Digitization of image/graphic information
For digitization of an image, the first is its electronicity, that is, the conversion of an optical image into an analog electrical signal. The process of digitizing an image is to first divide the image into pixels and then convert the corresponding signals of the pixels into binary 0/1 digital information. The image signal is converted into a digital signal through a process of sampling, quantization, and encoding.
In general, digital images represented by different-bit image signals have different color conditions. Each pixel of the black-and-white binary image is represented by 1-bit binary; black-and-white images with light-dark gradations are represented in 8-bit or 16-bit binary; whereas true-color images are mostly expressed in 3 or 4 8-bit binary representations. Rich color changes.
The description of graphic information is to graphically describe the contour of the graph with nodes, lines, and curves, and to indicate the status of its filling. Its description parameters are stored and transmitted digitally.
3. Digitization of page description information
Most of the print information is organized in the form of "pages" and "pages." Digitized page descriptions are indispensable for prepress processing.
An open, device-independent computer page description language is one of the cornerstones of digital prepress. It can describe the features and interrelationships of various graphic elements in the page. The purpose is to transfer the page information composed of graphic and textual information to the full, and ultimately "imaging" the specific device (display, printer, laser imagesetter, CTP equipment, etc.). In fact, the role of the page description language is to integrate the graphic information for the first time.
Among various page description languages, PostSript relies on its advantages to become an internationally accepted page description language. It has made outstanding contributions to the digitalization of printed information for more than a decade. However, with the advent of multimedia and Internet publishing, it also revealed its disadvantages. The PDF format is based on the PostSript imaging description model. It can integrate text, graphics, images, audio, and video information. It can form different types of publications according to different needs. It is gradually becoming the main format for digitalized page descriptions, especially in integrated formats. Digital flow related systems are widely used.
4. Digitization of production control information
Digitization of the necessary control information for printing production is based on the realization of electronic means, that is, the realization of single electronic control of printing and postpress equipment, and then the control information is expressed in binary digits to realize the “CNC” of the equipment.
Further requirements for digitally controlled printing equipment and postpress equipment are: on-line or off-line exchange of digital control information, ie, production control information can be transmitted to related equipment via the network or other storage media (disks, etc.). After the device receives this information, it also translates this information into action instructions that the device can perform in order to properly implement production.
Since there are many kinds of prepress, printing, and postpress equipment, and their features are different, the control methods and instructions are also different. Therefore, there is a need for a device-independent file format. In a file of this format, prepress